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HTML <script> Tag

Example

Output "Hello world" using JavaScript:

<script>
document.write("Hello World!")
</script>

Browser Support

All major browsers support the <script> tag.


Tag Definition and Usage

The <script> tag is used to define client-side scripts, such as JavaScript.

The <script> element either contains scripting statements or it points to an external script file through the src attribute.

JavaScript is commonly used for image manipulation, form validation, and dynamic content updates.


Tips and Notes

Note: If the src attribute is used, the <script> element must be empty.

Tip: See the <noscript> element for users who have disabled scripts in their browser or whose browser does not support client-side scripting.

Note: There are several ways to execute external scripts:


Differences Between HTML 4.01 and HTML5

In HTML 4, the type attribute is required, but in HTML5 it is optional.

The async attribute is new in HTML5.

Some attributes that were supported in HTML 4.01 are no longer supported in HTML5: xml:space.


Differences Between HTML and XHTML

In XHTML, the content type declaration is #PCDATA (instead of CDATA), meaning entities will be parsed.

This means that all special characters should be encoded or all content should be nested within a CDATA section in XHTML:

<script type="text/javascript">
//<![CDATA[
var i=10;
if (i&lt;5)
{
    // code content
}
//]]>
</script>

Attributes

Attribute Value Description
async New async Specifies that the script is executed asynchronously (only for external scripts).
charset charset Specifies the character encoding used in the script (only for external scripts).
defer defer Specifies that the script is executed when the page has finished parsing (only for external scripts).
src URL Specifies the URL of an external script.
type MIME-type Specifies the MIME type of the script.
xml:space preserve Not supported in HTML5. Specifies whether to preserve white space in the code.

Global Attributes

The <script> tag supports HTML's global attributes.


Related Articles

HTML Tutorial: HTML Scripts

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